At present the automotive industry is one of the most dynamically develping industrial branches; therefore, specialists constantly apply to non-traditional arrangements of engines and, in particular, to piston engines with an axial arrangement of cylinders. The advantages of the axial arrangement of cylinders in piston engines, bringing about smaller mass and overall dimensions of the engine, are well known. In relation to traditional piston engines with a crank mechanism for transforming the reciprocating motion of pistons into rotation of the crankshaft, the overall dimensions and mass of axial-piston engines are reduced 1.5-2.0 times, and conditions are provided for decreasing aerodynamic resistance of the vehicle owing to a decrease of the space occupied by the engine under the hood. However, the dimensions of the engine which occupies the space under the hood include, in particular, a pump that ensures lubrication of the engine and its accessories and made as a mounted unit. When this pump is made as an independent unit, it results in an increase of the engine mass, because the pump has its body and, besides, pipelines are necessary for feeding lubricant to the engine units and accessories. The provision of these pipelines, oil feed and outlet ducts and their joints brings about additional losses of energy for forcing the oil through them, which affects adversely the service life of both the engine and its units, particularly of the mechanism for transforming the rotation of the axial-piston engine shaft into the translational motion of stems of intake and exhaust valves.
Up to the present time, there is no reliable and durable design of the axial-piston engine, and there were rare attempts to create a durable design of the mechanism for transforming the rotary motion of its shaft into the translational motion of intake and exhaust valve stems.
Attempts to solve the problem of providing reliable operation of the axial-piston engine have resulted in the creation of an axial-piston machine (application DE, No. 3420529 A.sub.1).
The frame of the known machine houses a cylinder block with cylindrical cavities whose axes are parallel to the shaft longitudinal axis. The cavities accommodate pistons which can reciprocate therein, each whereof is hinged to one end of the connecting rod, whose other end is hinged to a swash plate. The latter is installed via a support on an inclined journal of the shaft mounted on supports installed in the frame. The swash plate is connected by a universal joint with the frame. The swash plate support on the shaft inclined journal is made spherical, which fact ensures swinging of the swash plate in the process of transforming the reciprocating motion of pistons into the rotary motion of the shaft.
Said application contains attempts of structural improvement of untis and accessories of the axial-piston engine and, in particular, of such vitally important unit thereof as the valve gear. The rotary motion of the shaft of the axial-piston machine in this case is transformed into the translational motion of intake and exhaust valve stems. The cavity of the transforming mechanism frame houses a drive gear whose teeth are cut on the crankshaft. The drive gear is meshed with a gear wheel which is installed in the frame on its own shaft. The latter is fitted with a gear which is in mesh with a wheel installed on the output shaft of the ignition system distributor drive reduction gear. A ring-shaped member is provided in the mechanism for transforming the shaft rotary motion into translational motion of valve stems of the axial-piston engine. The ring-shaped element is installed in the frame coaxially with the drive gear with a provision for rotating about its axle. Uniformly arranged on the inner surface of the ring-shaped member are radial profiled projections mating with its inner cylindrical surface and lying in the plane perpendicular to axis of the ring-shaped member. Each projection interacts with a roller connected to one arm of a double-arm lever, whose pin is fixed in the frame perpendicularly to the ring-shaped member axis. The other arm of the double-arm lever is intended for interaction with an actuating member, namely, with a valve stem, along its end face surface. The mechanism provides for a kinematic linkage of the gear wheel with the ring-shaped member. This linkage is constituted by engagement of the gear wheel teeth with the teeth made on the inner surface of the ring-shaped member.
This mechanism ensures transformation of the rotary motion of the crankshaft into translational motion of pistons of a seven-cylinder axial-piston machine. The gear ratio which depends on the number of cylinders and is ensured by the gearing of the mechanism increases along with the increase of the number of cylinders. Accordingly, there the pitch circle of the teeth made on the ring-shaped member also increases, which fact hampers the layout of the axial-piston engine.
Arrangement of projections on the ring-shaped member in one plane fails to provide the required valve timing angles. Operation of the motion-transforming mechanism is insufficiently reliable owing to a point contact of the spherical surface of the roller, installed on one of the arms of the double-arm lever, with the profiled surface of projections of the ring-shaped member, which brings about great contact stresses leading to chipping out of the profiled cam material. The clearance between the valve stem face and the surface of the second arm of the double-arm lever of the motion transforming mechanism is unadjustable, which leads either to breaking of the arm of the double-arm lever, or to the burn-out of the valve locking member.
To alter the swept volume of engine cylinders, there is a two-chamber gear pump communicated with a lubrication source and, through a duct made in the cylinder head, with a cavity of the hydraulic cylinder intended for moving the swash plate. Radial forces originated in the gearings of the two-chamber pump bring about great bending stresses in the crankshaft which, being of a small diameter caused by the small parameter of the drive gear due to the necessity to obtain a high gear ratio, worsens considerably the performance of the machine as a whole, thes preventing it from being used as an internal combustion engine.
Work aimed at improving the motion-transforming mechanism of the axial-piston engine and, particularly, at decreasing its axial dimensions and excluding a point contact in the roller--cam pair has resulted in the appearance of the mechanism according to SU, A, 591597.
Said mechanism is intended for use in an axial-piston engine, whose frame houses a cylinder block with cavities whose axes are parallel to the shaft longitudinal axis, and which accommodate reciprocating pistons. Each piston is kinematically linked with the engine shaft for transforming the reciprocating motion of pistons into a rotary motion of the shaft. In its turn, this motion is transformed into a translational motion of the intake and exhaust valve stems. For this purpose, crankshaft has teeth of the drive gear meshing with those of the gear wheels. Gear wheels are mounted on bearings fitted on the axles installed in the frame. The teeth are in mesh with those made on the inner surface of the ring-shaped member. The latter is installed in plain bearings on the frame coaxially with the drive gear with a provision for rotating relative to its axle. The external surface of the ring-shaped member carries radial projections conjugate to the external cylindrical surface of the ring-shaped member. The projections lie in two planes, each of which is perpendicular to the axle of the ring-shaped member. Circumferentially, the projections of different planes are displaced from one another through the same angle. The surface of each profiled projection interacts with the respective surface of the single-arm lever linearly, since the axle of each single-arm lever is secured in the frame and located parallel to the axle of the ring-shaped member. The single-arm lever has a flat surface which interacts with the surface of one arm of the double-arm lever. The axle of the double-arm lever is secured in the frame and located perpendicularly to the axle of the single-arm lever. The other arm of each double-arm lever has a surface for interacting with the end face of the stem of the respective valve of the axial-piston engine. Said axial-piston engine is provided with a pump for feeding oil to its friction surfaces drive by the crankshaft through a pulley and a belt. Inasmuch as the space confined inside the cylindrical surface whose generatrix is formed by the valve stem axles, and whose guide is the curve passing through the centres of their axles, is occupied by the mechanism for transforming the rotary motion of the shaft of the axial-piston engine into the translational motion of stems of engine intake and exhaust valves, the pump is located radially beyond this space, which increases the overall dimensions and mass of the engine. Owing to the fact that the pump is made as a separate unit, lubricating oil is fed to the friction surfaces of engine parts from the pump, which tells adversity on dependability of its performance due to oil lears through joints of said pipelines.